word files

sorry all i did search but i have a few questions and couldnt see straight cut answers

ive recently bought a macbook with leopard on it, it has iwork on it is this just a trial version? and is it really worth the money to buy it?

if i was to get neooffice is it? is it safe to run on leopard as i read there was some issues with it, cant remeber where tho. also will it save it to a .doc file for word or a file that microsoft excel will recognize. because unfortuanly like fair few i have to use a windows comp at work!